Getting recognized—getting heard— is actually tougher than ever. Although there are so many different avenues, networks, tools, and channels available for creating the unique voice—your personal brand—standing out from the crowd is just that much more difficult.
One way you can stand out, especially on sites like Twitter, is to have a great avatar. A great avatar will help people remember you instantly. And you should use it everywhere, across the board. Use it on your blog if you have one (you should). Use it on Twitter, Facebook, LinkedIn, everywhere. Even if people don’t automatically remember your name or your website, they’ll remember your avatar and make an association. When they see it again later, on another network or site, they’ll be more likely to pay attention, to friend you, and maybe remove a few of those degrees of separation.
Source: Why Your Avatar Matters